Phonograph motor



Jan. 15 1924. 1;480,553

E. B. HOFF PHONOGRAPH MOTOR I Filed July 5, 1922 \\\\\\||||IIII/ as w U 2::

HEWQN E). Hoff A INVENTOR.

Patented Jan. 15 1924.

NIT D STATES PATENT OFFICE.

MEL B. HOI'I', OI CLEVELAND, OHIO, ASSIGNOB TO THE AZOB MOTOR IANUI'AGIUB- ING COMPANY, 01 CLEVELAND, OHIO, A CORPORATION OF omo.

PHONOGRAIH MOTOR.

Application filed July 8,

To all whom. it may concern: Be it known that I, EARL B. Home, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Phonograph Motors, of which the following is a full, clear, and exact description, refeience being had to the accompanying drawings.

This invention relates to phonographs and has for its object the provision of a simple and self contained operating unit comprising a rotating disk and an alternating current motor, the parts being made of minimum vertical dimension so as to be adaptable to anv existing type and design of easing or cabinet, while eing of such design and construction as to produce a minimum of noise, either mechanically or electrically. Other objects of the invention are the provision of an alternating current motor of the maximum simplicity while further objects and advantages will become apparent as the description proceeds.

Previous attempts have been made to produce a device of the character just described and such devices have been successful so far as mechanical silence has been concerned but the same have been expensive to construct and not silent electrically. The magnetizin effect of an alternating current always ten s to produce a monotonous hum upon a pitch corresponding to the number of cycles per second, ordinarily about sixty. The loudness depends upon the shape of the magnetized parts, the flux density, the character and shape of adjacent metal parts, the mode of connection of those parts, and the existence of resonators of that pitch. This hum is ordinarily not objectionable but in connection with a musical instrument it would be insupportable Generally speak ing the way in which I minimize or prevent this ma etic hum is by making the cores of pecu iar sha e parallel to the moving part instead 0 perpendicular thereto as heretofore, and of such ample size as to reduce the flux density to a comparatively small value. This peculiar shape itself facilitates the desired increase of cross section, while to secure the necessary forceefi'ect I compensate for this decrease in flux density by presenting both ends of each 1922. Serial 10. 578,556.

core to the moving member and also by employing a magnetic bridge on the opposite side of said moving member.

In the drawings accompanyin and forming a part of this application Iliave shown certain physical forms in which my inventive idea can be embodied and b which the aforementioned objects may secured. Fig. 1 is a vertical central section through a phonograph unit made in accordance with my Invention; Fig. 2 is horizontal section along the line 2-2 of Fig. 1; Figs. 3 and 4 are dia ams showin modified forms of motor-e ements; and ig. 5 shows another form of attaching element.-

In these drawings 1 represents the motor base and 2 the rotatable plate or tum-table. The former is preferably made with projectin ears or corners 3, 3 for the reception 0 screws 4 by which it may be secured to a cabinet or other support. Many cabinets have a flat wooden to 5 formed with a circular hole therein sligl ftly smaller than the turntable which is designed to overlap the same at a short distance. My preferred mode of supporting my device in such a case is to suspend the ears 3 from vibrationless cushions 6 fastened around the same. In Fig. 1 I show cushions of rubber or similar material having nuts cast therein for the reception of the screws. In Fig. 5 I show a modified cushion 6 made of felt with metallic end members 7 clamped thereon.

The members 1 and 2 are preferabl die cast from alloy which exhibits good aring properties. Numerous compositions will occur to anyone skilled in the art of die casting. The plate 2 is formed with a central boss 10 in which is cast or fastened the pivot spindle 11 while the base 1 is formed with a central boss 12 havin a socket rotatabl receiving said spin le. One side of the base is formed with a recess 13 in which is journaled the usual governor 14 driven by a spiral gear 15 on the spindle.

The plate 2 is also formed with a seatin portion 16 having suitable studs 17 fastened thereto as by being cast therein or otherwise, and serving to secure in place the cylindrical conducting ring 18, a vibrationinsulating ring 19 of felt, rubber, or other obsorbing material being interposed. This ring is preferably made of copper and of considerable thickness, say three sixteenths to five sixteenths inch.

Carried by the base 1 at any convenient point is a core member comprising spaced pole pieces 20, 20 with wire-receiving portions 21 between them. These core mem-- necting portions 24 between the pole pieces,

It is only necessary that the connecting portions be spaced further from the ring than the pole pieces, and that the pole pieces match the first pole piece; otherwise the .bridge membercan be shaped substantially at will, and can even have coils 25 wound thereon as shown in Fig. 3, to supplement the eifect of the core opposite thereto. This produces, in effect, two pieces slotted as shown at 26 in Fig. 4 and the corresponding portion of each pole piece is surrounded by a short-circuited shielding coil 27. The core member and the bridging member are each built up of laminations parallel to the from sai plane of the plate 1, the'poles and bodies eing integral.

Having thus described my invention what I claim is:

1. In a phonograph motor, a cylindrical conducting band, a magnetizable core located on one side of said band and having spaced pole pieces, presented thereto, wire wound on said core between adjacent pole pieces, and a magnetizable bridge member located u on the opposite side of said band 5 pole pieces and having a pole piece opposite each of said first pole ieces, corresponding portions of all of sai pole pieces being magnetically shielded.

2. In a phonograph motor, a cylindrical conducting band, a magnetizable core 10- cated on one side of saidband and extend ing substantially parallel to the direction of motor thereof, said core having a plurality of pole pieces presented to said band and smaller portions between adjacent pole pieces having wire coils thereon, the axes of which are located circumferentially of said band, and a magnetizable bridge member located upon the opposite side of said band from said core, said bridge having pole pieces registering with said first pole pieces and presented close to the surface of the band and connecting portions integral with the pole pieces and spaced further from said hand, all of'said pole pieces havingshielded portions similarly arranged.

3. In a phonograph motor, a metallic conducting band having its opposed faces parallel and defining surfaces'of revolution, a core member having a plurality of pole pieces presented to one side of said band and smaller portions between and integral with said pole pieces and having wire coils wound thereon, a bridging member located upon the opposite side of said band and having pole pieces matching the first pole pieces, and connecting portions between said pole pieces, and means for producing a split magnetic phase in said poles.

4. In a phonograph motor, a metallic conducting band having its opposed faces par allel and defining surfaces of revolution, a pair of elongated parallel, magnetizable members located upon opposite sides of said band, each member having pole pieces which approach the corresponding pole pieces of the other member upon opposite sides of the band and connecting portions between said pole pieces spaced from the surface of said band, the connecting portions of at least one of said members being wound with wire,

and corresponding portions of all the pole pieces being magnetically shielded.

5. In a phonograph, in combination, a circular plate of non-magnetic metal, a vertical central spindle rotatably supporting said plate, acylindrical conducting band secured to said plate concentric with said spindle, the securing means including a vibration-insulating cushion, and a core member having its axis parallel to the direction of rotation of said band and having a plurality of poles, presented to the same surface of said band.

6. In a phonograph, in combination,. a circular plate mounted for axial rotation, a cylindrical conducting band rotatable therewith, a core member having a plurality of coils of wire wound thereon at spaced longitudinal points, there being a pole piece at each end of each coil presented to said band and the axes of the coils being substantially parallel to the adjacent portion of the band.

In testimony whereof, I hereunto affix my signature.

EARL B. HOFF. 

